net: atlantic: add msglevel configuration

We add ethtool msglevel configuration and change some
printouts to use netdev_info set of functions.

Signed-off-by: Nikita Danilov <ndanilov@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>